Leptin and mitogen-activated protein kinase (MAPK) in oocytes of sows and gilts

Leptin is a modulator of oocyte maturation and follicular development in swine. The MAPK are serine/threonine kinases that act as signal transduction pathways in swine ovaries. This study evaluated the presence of leptin, activated MAPK ERK 1/2 and p38 in oocytes of primordial/primary, secondary and tertiary follicles of gilts and sows. Ovaries from ten gilts and ten sows were collected in an abattoir, fixed in 10% formalin and prepared with classical histology methods. For immunohistochemistry, slides were incubated with polyclonal antibodies anti-leptin, anti-phospho ERK1/2 MAPK and anti-phospho p38 MAPK. Leptin immuno-labeling and the presence of activated ERK 1/2 MAPK were more intense for oocytes of sows (P0.05), whereas p38 MAPK was more active for oocytes of gilts (P0.05). Although no differences in immunolabeling for leptin and p38 MAPK were observed for oocytes of gilts at distinct follicle developmental stages (P0.05), immunolabeling was intense for oocytes of sows included in primordial/primary follicles (P0.05). Thus, leptin and p38 MAPK may be important to start oocyte development.